Fluid switch

ABSTRACT

The fluid switch controls the flow of a liquid from a funnel shaped receptacle and causes mixing of the liquid when the switch is in a &#39;&#39;&#39;&#39;closed&#39;&#39;&#39;&#39; position. The switch includes an air nozzle which extends into the receptacle and opens at a point adjacent a bottom outlet opening of the receptacle. The nozzle is adapted to direct an air stream toward and through the outlet opening to pre-empt liquid flow therethrough. A greater amount of air than is necessary to pre-empt flow of liquid through the outlet opening may be directed at the outlet opening so that the excess air bubbles through the liquid causing turbulence and mixing of the liquid prior to the &#39;&#39;&#39;&#39;opening&#39;&#39;&#39;&#39; of the switch.

United States Patent 11 1 Jones 1 Dec. 11, 1973 [73] Assignee: Coulter Chemistry, 1nc., Maunabo,

22 Filed; o1.21,1971

21 Appl.No.: 191,215

3,614,962 10/1971 Atkinson et a1. 137/815 Primary Examiner-Samuel Scott Attorney-J. Irving Silverman [57] ABSTRACT The fluid switch controls the flow of a liquid from a funnel shaped receptacle and causes mixing of the liquid when the switch is in a closed position. The switch includes an air nozzle which extends into the receptacle and opens at a point adjacent a bottom outlet opening of the receptacle. The nozzle is adapted to direct an air stream toward and through the outlet opening to pre-empt liquid flow therethrough. A greater amount of air than is necessary to pre-empt flow of liquid through the outlet opening may be directed at the outlet opening so that the excess air bubbles through the liquid causing turbulence and mixing of the liquid prior to the opening of the switch.

5 Claims, 2 Drawing Figures IIIIIIIIIIIIIIIJV III FLUID SWITCH BACKGROUND OF THE INVENTION The invention relates to a device herein referred to as a fluid switch for controlling the flow of liquid from a receptacle i.e. for switching the flow on and off, and for mixing the liquid while the flow of same from the receptacle is stopped.

More specifically the invention relates to a fluid switch of the type described which is adapted for use in flame photometry but which also can be utilized in particle counting,-viscosity measurements, etc.

In chemical or physical measurements of liquidliquid mixtures or liquid-solid suspension mixtures it is often required to achieve complete dispersion of the phases of the mixture prior to admitting the mixture to a measuring device or to a further processing device. For example, in the field of flame photometry it is desirable thoroughly to mix a liquid before atomizing the same and then directing the aerosol mixture into a flame.

This problem of incomplete or imperfect mixing of a solution is encountered, for example, in the analysis of human serum by means of flame photometry where a human serum is diluted in a solution of lithium carbonate. Accordingly it is the primary object of the present invention to provide a fluid switch which will adequately control the flow of a liquid from a receptacle. Preferably, prior to turning on the flow, that is to say when the switch is closed, the switch also functions thoroughly to mix the liquid.

SUMMARY OF THE INVENTION According to the invention there is provided a fluid switch including a receptacle having an inlet and an outlet. A device such as a nozzle extends into the receptacle and opens at a point within the receptacle proximate the outlet. The device is adapted to direct a gas stream at said outlet to control the flow of liquid from the receptacle through the outlet. Preferably the gas stream is coaxial with the outlet and the flow of gas into the receptacle may be greater than is needed for pre-empting liquid flow through the outlet such that the excess gas bubbles through the liquid to cause turbulence and mixing thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a s median sectional view of the fluid switch of the invention as used in an aerosol generator;

FIG. 2 is a fragmentary view of the bottom portion of the fluid switch shown in FIG. 1 on a greatly enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT The fluid switch of the invention is generally indicated at in FIG. 1 and includes a generally funnelshaped receptacle 12 which has a large mouth or inlet 14 at the top thereof. a smaller outlet 16 at the bottom of the funnel-shaped receptacle l2 and an intermediate converging portion 18 which converges to the outlet 16. As shown a feed tube 20 is connected to the outlet 16 of the receptacle l2 and forms part of an aerosol generator 21. In this respect the feed tube 20 has an outlet end 22 which is located proximate to the outlet end 24 of an aerosol air supply tube 26.

The aerosol generator 21 including the fluid switch 10 of the invention is particularly useful in a flame photometry system. In this respect, the aerosol formed by the high pressure air exiting from the end 24 of the aerosolair supply tube intersecting the liquid stream flowing from the end 22 of the feed tube 20 can be fed in a conventional manner to a flame where it is ignited. The color of the flame of the burning aerosol can then be analyzed for the purpose of making an analysis of the composition of the liquid or particles in the liquid mixture in the receptacle 12.

The switching and mixing mechanism of the fluid switch 10 includes a conduit 30 which extends downwardly into the receptacle l2 and opens at its lower end to provide a nozzle 32 proximate the outlet 16 of the receptacle 12. The upper end 34 of the conduit 30 is connected via the extension 36 to a suitable valve mechanism 38 which is adapted to connect a suitable source of air under pressure to the conduit 30.

Preferably and as shown in FIGS. 1 and 2 the conduit 30 is coaxial with the feed tube 20 such that the air stream exiting from the nozzle 32 will be coaxial with the outlet 16 of the receptacle 12. In this way the air stream from the nozzle 32 will better pre-empt the fluid which otherwise would flow through the feed tube 20.

In the operation of the fluid switch 10 the valve 38 is first actuated to connect the conduit 30 to the source of air under pressure so that an air stream is directed at the outlet 16 of the receptacle 12 and into and through the feed tube 20. Thereafter an imperfect mixture of liquids such as human serum diluted in a solution of lithium carbonate is delivered into the receptacle 12. The air stream flows through the tube 20 and pre-empts the flow of liquid through the tube 20. Under these circumstances the fluid switch is in a closed position preventing liquid from flowing out of the receptacle 12. Another source of compressed air is connected to the aerosol supply tube 26 to place the aerosol generator defined by the tubes 20 and 26 in a ready position.

Preferably, and in accordance with the teachings of the invention the volume of air flowing through the nozzle 32 is greater than the amount of air necessary to pre-empt the flow of liquid through the tube 20 such that there is an excess of air which bubbles through the liquid as shown by the bubbles 40 in FIGS. 1 and 2. This stream of bubbles through the liquid causes turbulence in the liquid and mixing of the liquid.

After a suitable interval of time the valve 38 is closed to stop the flow of air through the conduit 30 and the nozzle 32 allowing the now mixed liquid to be drawn into the aerosol generator feed tube 20 by gravity and by the aspirating effect of the air flowing from the air supply tube 26 past the outlet end 22 of the feed tube 20. The liquid is atomized and directed into the flame for excitation of elemental emission spectra.

Whenever the valve 38 is again turned on the air stream through the conduit 30 is re-established and a jet directed from the nozzle 32 at the outlet 16. This air stream will again pre-empt the aerosol feed tube 20 preventing liquid from flowing therethrough, thereby switching off the flow of fluid from the receptacle 12.

In order to convey an understanding of the general proportions of a practical device, for use with a flame photometer a fluid switch was constructed in which the receptacle 12 had a diameter of about I inch and a capacity of about 7cc. The tubes 26 and 30 and the conduit 30 were of capillary internal dimension, i.e., of the order of 0.020 inch in inside diameter. Other dimensions can be approximated from the drawing.

It is to be noted that in addition to providing switching and mixing functions the fluid switch of the invention also provides a cleansing function in that the air directed at and through the feed tube serves to cleanse the tube of liquid material and keeps the same free for the flow of liquid when the air stream is turned off.

From the foregoing description it will be obvious to those skilled in the art of fluid control systems that obvious modifications and variations can be made to the fluid switch of the invention without departing from the spirit or scope of the invention. Accordingly the scope of the invention is only to be limited as necessitated by the accompanying claims.

What it is desired to secure by Letters Patent of the United States is:

l. A fluid switch including a liquid dispensing receptacle having an inlet therein and an outlet adjacent the bottom thereof, a gas stream directing conduit extending into said receptacle having a discharge nozzle at one end fixed in position proximate said outlet, gas pressure supply means in communication with the other end of said conduit for delivering a quantity of gas through said nozzle and said outlet to preempt the flow of liquid through said outlet, said gas quantity being in excess of that needed to preempt liquid flow so that said excess will bubble through the liquid in said receptacle to cause turbulence and mixing of the liquid, and means to close off the gas flow to permit liquid flow through said outlet.

2. The fluid switch as claimed in claim 1 wherein said means to close off the gas flow includes valve means in said conduit.

3. The fluid switch as claimed in claim 1 wherein said conduit is coaxial with said outlet.

4. The fluid switch as claimed in claim 1 wherein said receptacle is a funnel which converges toward said outlet.

5. The fluid switch as claimed in claim 4 wherein said outlet includes a tube at the lower end of said funnel. 

1. A fluid switch including a liquid dispensing receptacle having an inlet therein and an outlet adjacent the bottom thereof, a gas stream directing conduit extending into said receptacle having a discharge nozzle at one end fixed in position proximate said outlet, gas pressure supply means in communication with the other end of said conduit for delivering a quantity of gas through said nozzle and said outlet to preempt the flow of liquid through said outlet, said gas quantity being in excess of that needed to preempt liquid flow so that said excess will bubble through the liquid in said receptacle to cause turbulence and mixing of the liquid, and means to close off the gas flow to permit liquid flow through said outlet.
 2. The fluid switch as claimed in claim 1 wherein said means to close off the gas flow includes valve means in said conduit.
 3. The fluid switch as claimed in claim 1 wherein said conduit is coaxial with said outlet.
 4. The fluid switch as claimed in claim 1 wherein said receptacle is a funnel which converges toward said outlet.
 5. The fluid switch as claimed in claim 4 wherein said outlet includes a tube at the lower end of said funnel. 